xref: /freebsd/usr.bin/tail/misc.c (revision cc16dea626cf2fc80cde667ac4798065108e596c)
1 /*-
2  * Copyright (c) 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Edward Sze-Tyan Wang.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 4. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #include <sys/cdefs.h>
34 
35 __FBSDID("$FreeBSD$");
36 
37 #ifndef lint
38 static const char sccsid[] = "@(#)misc.c	8.1 (Berkeley) 6/6/93";
39 #endif
40 
41 #include <sys/types.h>
42 #include <sys/stat.h>
43 #include <sys/mman.h>
44 
45 #include <err.h>
46 #include <errno.h>
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <string.h>
50 #include <unistd.h>
51 
52 #include "extern.h"
53 
54 void
55 ierr(const char *fname)
56 {
57 	warn("%s", fname);
58 	rval = 1;
59 }
60 
61 void
62 oerr(void)
63 {
64 	err(1, "stdout");
65 }
66 
67 /*
68  * Print `len' bytes from the file associated with `mip', starting at
69  * absolute file offset `startoff'. May move map window.
70  */
71 int
72 mapprint(struct mapinfo *mip, off_t startoff, off_t len)
73 {
74 	int n;
75 
76 	while (len > 0) {
77 		if (startoff < mip->mapoff || startoff >= mip->mapoff +
78 		    (off_t)mip->maplen) {
79 			if (maparound(mip, startoff) != 0)
80 				return (1);
81 		}
82 		n = (mip->mapoff + mip->maplen) - startoff;
83 		if (n > len)
84 			n = len;
85 		WR(mip->start + (startoff - mip->mapoff), n);
86 		startoff += n;
87 		len -= n;
88 	}
89 	return (0);
90 }
91 
92 /*
93  * Move the map window so that it contains the byte at absolute file
94  * offset `offset'. The start of the map window will be TAILMAPLEN
95  * aligned.
96  */
97 int
98 maparound(struct mapinfo *mip, off_t offset)
99 {
100 
101 	if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
102 		return (1);
103 
104 	mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
105 	mip->maplen = TAILMAPLEN;
106 	if ((off_t)mip->maplen > mip->maxoff - mip->mapoff)
107 		mip->maplen = mip->maxoff - mip->mapoff;
108 	if (mip->maplen <= 0)
109 		abort();
110 	if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
111 	     mip->fd, mip->mapoff)) == MAP_FAILED)
112 		return (1);
113 
114 	return (0);
115 }
116 
117 /*
118  * Print the file name without stdio buffering.
119  */
120 void
121 printfn(const char *fn, int print_nl)
122 {
123 
124 	if (print_nl)
125 		WR("\n", 1);
126 	WR("==> ", 4);
127 	WR(fn, strlen(fn));
128 	WR(" <==\n", 5);
129 }
130